[v2,2/7] bus: Introduce firewall controller framework

diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 50200d1c06ea..d3f636c64e1c 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -203,4 +203,6 @@  config DA8XX_MSTPRI
 
 source "drivers/bus/fsl-mc/Kconfig"
 
+source "drivers/bus/firewall/Kconfig"
+
 endmenu
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index 1320bcf9fa9d..278c27fd57cd 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -34,3 +34,5 @@  obj-$(CONFIG_UNIPHIER_SYSTEM_BUS)	+= uniphier-system-bus.o
 obj-$(CONFIG_VEXPRESS_CONFIG)	+= vexpress-config.o
 
 obj-$(CONFIG_DA8XX_MSTPRI)	+= da8xx-mstpri.o
+
+obj-$(CONFIG_FIREWALL_CONTROLLERS) 	+= firewall/
diff --git a/drivers/bus/firewall/Kconfig b/drivers/bus/firewall/Kconfig
new file mode 100644
index 000000000000..893bacb955f5
--- /dev/null
+++ b/drivers/bus/firewall/Kconfig
@@ -0,0 +1,7 @@ 
+menu "Bus Firewall Controllers"
+
+config FIREWALL_CONTROLLERS
+	bool "Support of bus firewall controllers"
+	depends on OF
+
+endmenu
diff --git a/drivers/bus/firewall/Makefile b/drivers/bus/firewall/Makefile
new file mode 100644
index 000000000000..eb6b978d6450
--- /dev/null
+++ b/drivers/bus/firewall/Makefile
@@ -0,0 +1 @@ 
+obj-$(CONFIG_FIREWALL_CONTROLLERS) += firewall.o
diff --git a/drivers/bus/firewall/firewall.c b/drivers/bus/firewall/firewall.c
new file mode 100644
index 000000000000..765105d29075
--- /dev/null
+++ b/drivers/bus/firewall/firewall.c
@@ -0,0 +1,264 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) STMicroelectronics 2020 - All Rights Reserved
+ * Author: Benjamin Gaignard <benjamin.gaignard@st.com> for STMicroelectronics.
+ */
+
+#include <linux/device.h>
+#include <linux/firewall.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+/* Mutex taken to protect firewall_list */
+static DEFINE_MUTEX(firewall_list_mutex);
+
+/* Global list of firewall control devices */
+static LIST_HEAD(firewall_list);
+
+struct firewall_ctrl {
+	struct list_head node;
+	struct device *dev;
+	struct firewall_ops *ops;
+};
+
+static struct firewall_ctrl *get_firewallctrl_from_node(struct device_node *np)
+{
+	struct firewall_ctrl *ctrl;
+
+	mutex_lock(&firewall_list_mutex);
+
+	list_for_each_entry(ctrl, &firewall_list, node) {
+		if (ctrl->dev->of_node == np) {
+			mutex_unlock(&firewall_list_mutex);
+			return ctrl;
+		}
+	}
+
+	mutex_unlock(&firewall_list_mutex);
+
+	return NULL;
+}
+
+/**
+ * firewall_dt_has_default
+ *
+ * Check if the device node provide firewall configuration
+ *
+ * @dev: device with possible firewall configuration
+ *
+ * Return: true is firewall-0 property exist in the device node
+ */
+static bool firewall_dt_has_default(struct device *dev)
+{
+	struct device_node *np;
+	struct property *prop;
+	int size;
+
+	np = dev->of_node;
+	if (!np)
+		return false;
+
+	prop = of_find_property(np, "firewall-0", &size);
+
+	return prop ? true : false;
+}
+
+/**
+ * firewall_set_config_by_index
+ *
+ * Set a firewall controller configuration based on given index.
+ *
+ * @dev: device with firewall configuration to apply.
+ * @index: the index of the configuration in device node.
+ *
+ * Return: 0 if OK, -EPROBE_DEFER if waiting for firewall controller to be
+ * registered or negative value on other errors.
+ */
+int firewall_set_config_by_index(struct device *dev, int index)
+{
+	struct device_node *np = dev->of_node;
+	char *propname;
+	int configs, i, err = 0;
+
+	if (!np)
+		return 0;
+
+	propname = kasprintf(GFP_KERNEL, "firewall-%d", index);
+	configs = of_count_phandle_with_args(np, propname, "#firewall-cells");
+	if (configs < 0) {
+		err = -EINVAL;
+		goto error;
+	}
+
+	for (i = 0; i < configs; i++) {
+		struct firewall_ctrl *ctrl;
+		struct of_phandle_args args;
+
+		err = of_parse_phandle_with_args(np, propname,
+						 "#firewall-cells",
+						 i, &args);
+		if (err)
+			goto error;
+
+		/* Test if the controller is (or will be) available */
+		if (!of_device_is_available(args.np)) {
+			of_node_put(args.np);
+			continue;
+		}
+
+		ctrl = get_firewallctrl_from_node(args.np);
+		of_node_put(args.np);
+
+		/* Controller is not yet registered */
+		if (!ctrl) {
+			err = -EPROBE_DEFER;
+			goto error;
+		}
+
+		err = ctrl->ops->set_config(ctrl->dev, &args);
+		if (err)
+			goto error;
+	}
+
+error:
+	kfree(propname);
+	return err;
+}
+EXPORT_SYMBOL_GPL(firewall_set_config_by_index);
+
+/**
+ * firewall_set_config_by_name
+ *
+ * Set a firwall controller configuration based on given name.
+ *
+ * @dev: device with firewall configuration to apply.
+ * @name: the name of the configuration in device node.
+ *
+ * Return: 0 if OK, -EPROBE_DEFER if waiting for firewall controller to be
+ * registered or negative value on other errors.
+ */
+int firewall_set_config_by_name(struct device *dev, char *name)
+{
+	const char *configname;
+	int count, i;
+
+	count = of_property_count_strings(dev->of_node, "firewall-names");
+	for (i = 0; i < count; i++) {
+		int err;
+
+		err = of_property_read_string_index(dev->of_node,
+						    "firewall-names",
+						    i, &configname);
+		if (err)
+			return err;
+
+		if (strcmp(name, configname))
+			continue;
+
+		return firewall_set_config_by_index(dev, i);
+	}
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(firewall_set_config_by_name);
+
+/**
+ * firewall_set_default_config
+ *
+ * Set the default configuration for device.
+ * First try to apply configuration named "default", if it fails
+ * or doesn't exist, try to apply firewall-0 configuration.
+ *
+ * @dev: device with firewall configuration to apply.
+ *
+ * Return: 0 if OK, -EPROBE_DEFER if waiting for firewall controller to be
+ * registered or negative value on other errors.
+ */
+int firewall_set_default_config(struct device *dev)
+{
+	int ret;
+
+	/* Nothing to do if device node doesn't contain at least
+	 * one configuration
+	 */
+	if (!firewall_dt_has_default(dev))
+		return 0;
+
+	ret = firewall_set_config_by_name(dev, "default");
+	if (!ret || (ret == -EPROBE_DEFER))
+		return ret;
+
+	return firewall_set_config_by_index(dev, 0);
+}
+EXPORT_SYMBOL_GPL(firewall_set_default_config);
+
+/**
+ * firewall_register
+ *
+ * Register a firewall controller device.
+ *
+ * @dev: device implementing firewall controller.
+ * @ops: firewall controller operations.
+ *
+ * Return: 0 if OK or negative value on error.
+ */
+int firewall_register(struct device *dev,
+		      struct firewall_ops *ops)
+{
+	struct firewall_ctrl *ctrl;
+
+	if (!dev || !ops || !ops->set_config)
+		return -EINVAL;
+
+	ctrl = kzalloc(sizeof(*ctrl), GFP_KERNEL);
+	if (!ctrl)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&ctrl->node);
+
+	ctrl->dev = dev;
+	ctrl->ops = ops;
+
+	mutex_lock(&firewall_list_mutex);
+	list_add_tail(&ctrl->node, &firewall_list);
+	mutex_unlock(&firewall_list_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(firewall_register);
+
+/**
+ * firewall_unregister
+ *
+ * Unregister a firewall controller device.
+ *
+ * @dev: device implementing firewall controller.
+ */
+void firewall_unregister(struct device *dev)
+{
+	struct firewall_ctrl *ctrl;
+
+	ctrl = get_firewallctrl_from_node(dev->of_node);
+	if (!ctrl)
+		return;
+
+	mutex_lock(&firewall_list_mutex);
+	list_del(&ctrl->node);
+	mutex_unlock(&firewall_list_mutex);
+
+	kfree(ctrl);
+}
+EXPORT_SYMBOL_GPL(firewall_unregister);
+
+static int __init firewall_init(void)
+{
+	pr_info("initialized bus firewall controller subsystem\n");
+	return 0;
+}
+
+/* Init early since drivers really need to configure firewall early */
+core_initcall(firewall_init);
diff --git a/include/linux/firewall.h b/include/linux/firewall.h
new file mode 100644
index 000000000000..67eb9985821c
--- /dev/null
+++ b/include/linux/firewall.h
@@ -0,0 +1,70 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) STMicroelectronics 2020 - All Rights Reserved
+ * Author: Benjamin Gaignard <benjamin.gaignard@st.com> for STMicroelectronics.
+ */
+
+#ifndef _FIREWALL_H_
+#define _FIREWALL_H_
+
+#include <linux/device.h>
+#include <linux/of.h>
+
+/**
+ * struct firewall_ops
+ *
+ * Firewall controller operations structure to be filled by drivers.
+ */
+struct firewall_ops {
+	/**
+	 * @set_config:
+	 *
+	 * Driver callback to set a firewall configuration on a controller.
+	 * Configuration arguments are provided in out_args parameter.
+	 *
+	 * Return: 0 on success, a negative error code on failure.
+	 */
+	int (*set_config)(struct device *dev, struct of_phandle_args *out_args);
+};
+
+#ifdef CONFIG_FIREWALL_CONTROLLERS
+
+int firewall_set_config_by_index(struct device *dev, int index);
+int firewall_set_config_by_name(struct device *dev, char *name);
+int firewall_set_default_config(struct device *dev);
+
+int firewall_register(struct device *dev, struct firewall_ops *ops);
+
+void firewall_unregister(struct device *dev);
+
+#else
+
+static inline int firewall_set_config_by_index(struct device *dev, int index)
+{
+	return 0;
+}
+
+static inline int firewall_set_config_by_name(struct device *dev, char *name)
+{
+	return 0;
+}
+
+static inline int firewall_set_default_config(struct device *dev)
+{
+	return 0;
+}
+
+static inline int firewall_register(struct device *dev,
+				    struct firewall_ops *ops)
+{
+	return 0;
+}
+
+static inline void firewall_unregister(struct device *dev)
+{
+	/* Empty */
+}
+
+#endif
+
+#endif /* _FIREWALL_H_ */